- 1Enter the electrical device power consumption in Watts (W).
- 2Enter the average operating hours per day (0 to 24).
- 3Enter your electricity rate in dollars per kilowatt-hour ($ / kWh).
- 4View estimated daily, monthly, and annual energy consumption (kWh) and costs ($).
Utility companies bill electricity based on kilowatt-hours (kWh), which measure total electrical energy consumed over time. One kilowatt-hour equals 1,000 Watts of power used continuously for one hour.
Converts Watts to kilowatts and multiplies by daily operating hours.
Daily kWh = (Power in Watts × Hours per Day) / 1,000Uses the calculator model factor of 30.4375 average days per month.
Monthly kWh = Daily kWh × 30.4375Uses the calculator model factor of 365.25 average days per year.
Annual kWh = Daily kWh × 365.25Multiplies energy consumption by electricity rate.
Cost ($) = kWh × Rate ($ / kWh)Daily kWh = (1500 × 4) / 1000 = 6.0 kWh/day → Daily Cost = 6.0 × 0.14 = $0.84
Monthly kWh = 6.0 × 30.4375 = 182.6 kWh → Monthly Cost = $25.57
Annual kWh = 6.0 × 365.25 = 2,191.5 kWh → Annual Cost = $306.81Daily kWh = 800 × 6 / 1000 = 4.8; Daily cost = 4.8 × 0.15 = 0.72; Annual = 4.8 × 365.25 × 0.15Daily kWh = 16; Monthly kWh = 16 × 30.4375 = 487; Monthly cost = 487 × 0.18- Average days factors: Monthly and annual consumption use exact calendar average multipliers of 30.4375 days/month and 365.25 days/year.
- Electricity rate assumption: The rate field defaults to $0.14/kWh as an input placeholder, not a universal energy price. Enter your local utility rate.
- Utility bill differences: Actual utility bills may include fixed customer charges, tiered usage pricing, time-of-use (TOU) rates, demand fees, and local taxes not modeled here.
How do I convert Watts to Kilowatts?
Divide the power in Watts by 1,000. For example, 1,500 W / 1,000 = 1.5 kW.
Why does the calculator use 30.4375 days for a month?
30.4375 is the precise average number of days per month in a 365.25-day year (365.25 / 12), ensuring consistency across annual and monthly costs.
How are monthly and annual costs projected?
From the daily kilowatt-hours: monthly multiplies by 30.4375 (average days per month) and annual by 365.25 (average days per year), then each is multiplied by the price per kWh.
What are the input limits?
Power and price per kWh must be zero or positive, and hours per day must be between 0 and 24.
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